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Chemical Name: Methyl Ethyl Ketone
Chemical Formula: C4H8O
Other Names: 2-Butanone, MEK
Use Cases: Solvent for resins, coatings, adhesives, cleaning fluids, and chemical intermediates. Many workers encounter this in paint thinners, varnishes, and industrial degreasers. Its distinct odor often travels far in poorly ventilated spaces, and even people unfamiliar with chemistry notice it quickly, a fact field experience confirms again and again.
Physical State: Clear, colorless liquid, acetone-like scent
Hazard Class: Flammable liquid, category 2
Key Dangers: Rapid evaporation leads to inhalation risks, even in outdoor settings. Regular skin contact triggers irritation or dermatitis. High vapor concentrations bring headaches, nausea, central nervous system effects. In enclosed workplaces or garages, fire hazards jump due to low ignition temperature and high vapor pressure. MEK vapors can travel to ignition sources, flashing back unexpectedly.
Pictograms: Flame, Health Hazard
Signal Words: Danger
Main Ingredient: Methyl Ethyl Ketone (CAS 78-93-3) usually over 99%
Impurities: Minor content of water or related ketones dependent on production
Most batches in industrial or laboratory use stick with the pure solvent, which means safety steps remain consistent for nearly every drum or canister workers pop open on site.
Inhalation: Move victim to fresh air. Observe for breathing difficulty or dizziness. Oxygen or medical help for persistent symptoms.
Skin Contact: Remove contaminated clothing, rinse skin thoroughly with water and soap. Extended exposure may dry or crack the skin.
Eye Contact: Flush eyes with water for at least fifteen minutes. Remove contact lenses for better irrigation.
Ingestion: Seek medical attention, rinse mouth if conscious, but do not induce vomiting. Workers often underestimate ingestion risks, especially in spaces where hand-to-mouth behaviors slip in, like food break rooms adjacent to work sites.
Extinguishing Media: Carbon dioxide, dry chemical, foam. Water spray cools containers but can spread liquid fires.
Fire Hazards: Vapors can ignite even distant from a direct flame. Flash point sits around -9°C, so open flames, even static, find an easy target in MEK spills.
Protective Equipment: Firefighters gear up with full-face respirators and chemical-resistant suits, given the toxic fumes combustion releases.
Personal Experience: Years spent in fire safety drills have shown how fast MEK-steeped rags or spills can turn a minor incident into a dangerous blaze, especially alongside welding or grinding.
Personal Protection: Wear respiratory, skin, and eye protection before cleanup. Evacuate non-essential people.
Ventilation: Open windows, deploy fans – vapors drop fire risk and reduce inhalation hazards quickly this way.
Spill Cleanup: Use inert absorbents (sand, vermiculite). Place materials in approved containers. Avoid flooding drains; MEK migrates rapidly through soil or concrete gaps.
Experience-Based Note: Response speed has a real impact. The longer MEK sits, the more difficult air clearing becomes, and the bigger the area needing decontamination grows.
Safe Handling: Use in well-ventilated areas. Ground containers to avoid static. Never eat, drink, or smoke near MEK. Respiratory and skin protection prevent injuries found in both old hands and new hires.
Storage: Store in cool, dry, fireproof locations, away from strong acids, bases, and oxidizers. Containers must stay tightly closed. Drums stored near open flames or heaters create the kind of accident no one forgets.
Experience Highlight: Fieldwork consistently shows that labeling, routine inspection, and basic common sense – like separating flammables from hot work areas – saves both product and lives.
Engineering Controls: Mechanical exhaust ventilation keeps levels below occupational limits.
Personal Protection: Chemical goggles or face shields, nitrile gloves, protective clothing for splash risk. Respirators for high vapor concentrations or confined spaces. MEK seeps quickly through latex but not nitrile, a detail sometimes missed in workplaces.
Occupational Limits: OSHA and ACGIH suggest exposure limits near 200 ppm as an 8-hour TWA. On busy job sites or closed tanks, monitors help keep tabs.
Appearance: Colorless liquid
Odor: Sharp, sweet, similar to acetone
Boiling Point: About 80°C (176°F)
Melting Point: -86°C (-123°F)
Vapor Pressure: High; evaporates swiftly
Solubility: Slightly soluble in water, mixes with many organic solvents
MEK’s volatility stands out on job sites. Evaporation leaves fumes lingering, making air handling a permanent concern in hot weather or small rooms.
Stability: Generally stable under normal conditions
Incompatibles: Strong oxidizing agents, acids, bases, peroxides
Hazardous Byproducts: Fumes of carbon monoxide, carbon dioxide, sometimes toxic ketones
Aggressive reactions show up easily if stored wrong or mixed carelessly, a problem facility managers can’t afford to overlook.
Short-Term Exposure: Irritation to eyes, skin, upper respiratory tract, headaches, dizziness from vapor
Long-Term Exposure: Potential for liver or kidney effects, skin disorders
Route of Entry: Inhalation, skin absorption, eye or digestive contact
Years of occupational monitoring reveal that adequate protection and training dramatically cut injuries, but occasional carelessness still results in preventable hospital visits.
Environmental Fate: MEK degrades rapidly in air by reacting with hydroxyl radicals, but in large volume spills, especially to soil or water, it poses moderate threat to aquatic life.
Bioaccumulation: Not significant—breaks down fairly quickly, but acute exposure to surface water may still kill local organisms.
Rural spills run straight to groundwater, requiring containment and notification. Cleanup efforts after significant leaks highlight persistent concerns for small water systems and local agriculture.
Preferred Methods: Incineration in licensed facilities, not landfill or routine drains
Special Steps: Only approved waste handlers should manage bulk disposal; improper dumping leads to fines and environmental damage.
Waste audits often find that clear policies, combined with signage and dedicated containers, massively reduce illegal dumping or mismanaged quenching of rags and containers.
UN Number: 1193
Class: 3 (Flammable liquids)
Packing Group: II
Containers must be clearly labeled, leak-tested, and shipped under tight temperature control where possible. Field shipments should avoid exposure to direct sun or proximity to ignition. Truck fires from loose jugs are rare but unforgettable.
US Standards: Listed under OSHA, EPA, and DOT for workplace safety, emissions, and hazardous materials shipment.
International Standards: Compliance required under various EU, Canadian, and Asian environment laws
Worksite audits regularly catch missing documentation, reinforcing the routine review of regulatory rules. Digital tracking helps now, but regular review stands essential to keep fines and workplace accidents off the payroll.
